Note: Descriptions are shown in the official language in which they were submitted.
CA 02260441 1999-O1-27
FIELD OF THE INVENTION
The present invention relates to a setting tool
for driving nail-shaped fastening elements into hard
constructional components and including a guide cylinder, a
drive piston axially displaceable in the guide cylinder, a
guide housing a slide displaceable in the guide housing and
having a pawl cooperating with a stop surface provided on
the drive piston and pivotable out of an axial projection of
the drive piston against a biasing force applied by a spring
member, and an operating cam cooperating with a control
profile provided on the pawl for retaining the pawl out of
the axial projection of the drive piston.
BACKGROUND OF THE INVENTION
For driving nail-shaped fastening components into
hard constructional components such as concrete, stone, or
steel and the like, setting tools, which are operated by
high-pressure gases, are used. In widely used and
preferred, from the standpoint of safety, setting tools, the
high-pressure gases act on a drive piston which, in turn,
drives a to-be-driven fastening element into a hard
constructional component. While these tools have
significant advantages, they also have a serious drawback
which consists in that the drive piston should be pushed
back in its initial position after each drive-in process.
German Patent no. 2,026,293 discloses an explosive
powder charge-operated setting tool in which the drive
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piston is returned to its initial position after each
setting process manually. In this setting tool, a slide is
displaced in a guide housing with a handle accessible from
outside of the setting tool. A tension spring connects the
slide with a front, in a setting direction, region of the
guide housing. The slide includes a pawl pivotable into the
axial projection of the drive piston by a spring member when
the slide is displaceable with the handle in a direction
opposite to the setting direction. When the slide is in its
initial position, a control profile provided on the pawl
cooperates with an operating cam which retains the pawl from
projecting into the axial projection of the drive piston.
This type of returning of the drive piston into
its initial position is very cumbersome and can be dangerous
when simultaneously with the displacement of the slide with
the handle in a direction opposite to the setting direction,
a new cartridge is ignited.
Accordingly, an object of the present invention is
a high-pressure gas-operated setting tool in which the drive
piston automatically returns to its initial position after
each setting process.
BRIEF SUN~iARY OF THE INVENTION
This and other objects of the present invention,
which will become apparent hereinafter, are achieved by
providing a setting tool including a guide cylinder, a drive
piston axially displaceable in the guide cylinder, a guide
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housing, and a slide displaceable in the guide housing
against a spring-biasing force acting in a direction
opposite to a setting direction. The slide has a pawl
cooperating with a stop surface provided on the drive piston
and pivotable out of an axial projection of the drive piston
against a biasing force applied by a spring member. An
operating cam is provided in an end region of the guide
cylinder opposite to the setting direction, and the pawl has
a control profile cooperating with the operating cam whereby
the pawl is pivoted out of the axial projection of the drive
piston. At least one connection channel connects an end
region of the guide housing, which is opposite to the
setting direction with the guide cylinder.
In the inventive setting tool, the high-pressure
gas drives not only the drive piston in the setting
direction but also the slide. The pawl, which is arranged
on the slide, has a control profile which cooperates with
the operating cam which prevents the pawl from projecting
into the axial projection of the drive piston. This insures
unhindered displacement of the drive piston, which has a
higher acceleration than the slide, in the setting direction
by a high-pressure gas.
When the slide is displaced, together with the
drive piston, in a setting direction, the control profile of
the pawl becomes disengaged from the operating cam, and a
spring member, which is arranged between the pawl and the
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slide, pivots the pawl into the axial projection of the
drive piston. The slide reaches its end position at the
earliest after the drive piston already reached the end, in
the setting direction, region of the guide cylinder or has
rebound from the fastening element and has been accelerated
toward its initial position by the stored residual power.
Upon its displacement back to its initial
position, the drive piston engages the pawl which projects
into the axial projection of the drive piston. In order to
prevent clinging of the drive piston to the pawl, the pawl
is provided with an inclined, in a setting direction,
surface that provides for pivoting of the pawl out of the
axial projection of the drive piston during the combined
displacement of both the drive piston and the slide to their
respective initial positions until the drive piston passes
past the pawl.
A spring which, e.g., is formed as a compression
or scroll spring and is compressed upon displacement of the
slide in the setting direction, pushes the slide, after it
has reached its end, in the setting direction, position,
back to its initial position. The drive piston, which has
not yet reached its initial position, has its stop surface
engaged by the pawl which pushes the drive piston to its
initial position. Shortly before the slide reaches its
initial position, the control profile of the pawl engages
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the operating cam which pivots the pawl completely out of
the axial projection of the drive piston.
A time-delayed acceleration of the slide relative
to the drive piston is achieved by providing advantageously
a connection channel that opens radially into the guide
cylinder at a location spaced axially in the setting
direction from the bottom of the guide cylinder which faces
in the setting direction.
A uniform distribution of the high-pressure gas in
the end region of the guide channel, which is formed the
guide housing, is preferably achieved by providing a
connection channel which opens into the bottom of the guide
channel facing in the setting direction. The slide can,
e.g., be provided with a distribution chamber formed at the
free end of the slide opposite to the setting direction and
serving for accommodating the expansion of the high-pressure
gas before the acceleration of the slide in the setting
direction takes place.
In setting tools in which for setting fastening
elements having different length, different propellant gas
pressures are needed, advantageously, two connection
channels open into the guide housing, with one channel being
associated with a vent channel the cross-section of which is
varied with an adjusting member. The vent channel extends
between the guide cylinder and, the atmosphere. The second
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channel is spaced axially, in the setting direction, from
the vent channel and opens into the guide cylinder. The two
connection channels serve for directing a portion of a high-
pressure gas into the guide housing where it applies the
same pressure to the slide independent of the position of
the adjusting member relative to the vent channel or
independent of the pressure established in the guide
cylinder with the adjusting member. This provides for
displacement of the slide in the setting direction with a
uniformly accelerated speed.
When, e.g., the entire energy of the high-pressure
gas is necessary for the displacement of the drive piston in
the guide cylinder, the adjusting member is in its closed
position, and the vent channel is closed. With the vent
channel being closed, the entire amount of the high-pressure
gas necessary for the acceleration of the slide is delivered
into the guide housing through the second connection
channel. When a smaller pressure is needed in the guide
cylinder for displacing the drive piston, at least partial
opening of the vent channel is effected by the displacement
of the adjusting member in a direction opposite to the
setting direction. In this case, the high-pressure gas
needed for the displacement of the slide is delivered
through the first and second connection channels.
To simplify the manufacturing and to reduce
manufacturing costs, advantageously, the adjusting member is
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displaceable transverse to the longitudinal axis of the vent
channel.
In order to provide for a form-locking engagement
of_ the pawl, which is arranged on the slide, with the drive
piston when the slide is displaced to its initial position,
advantageously, the inner chambers of both the guide
cylinder and the guide channel, which is formed in the guide
housing, are connected with each other by respective
elongate slots extending parallel to the longitudinal axis
of the drive piston. Through these slots, the pawl can
project into the inner chamber of the guide cylinder, i.e.,
into the axial projection of the drive piston.
For the sake of simplification of the
manufacturing, advantageously, both the guide channel of the
guide housing and the slide have a circular cross-section.
To prevent a pivotal movement of the slide in the
guide channel, advantageously, the guide housing is provided
with a slot extending parallel to the axis of the drive
piston, and the slide is provided with a guide member
projecting through the slot.
To simplify manufacturing, advantageously the
guide member is formed as a bolt.
IN THE DRAWINGS
The features and objects of the present invention
will become more apparent, and the invention itself will be
the best understood from the following detailed description
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of the preferred embodiment when read with reference to the
accompanying drawings, wherein:
Fig. 1 shows a schematic side elevational view
of a setting tool according to the
present invention;
Fig. 2 shows a cross-sectional view of a
portion of the setting tool shown in
Fig. 1 at an increased scale in the
initial position of the tool;
Fig. 3 shows a cross-sectional view of the same
portion of the setting tool shown in
Fig. 2 in the position of the tool
immediately after the beginning of the
setting process;
Fig. 4 shows a cross-sectional view of the same
portion of the setting tool shown in
Figs. 2 and 3 after the setting process
has ended; and
Fig. 5 shows a cross-sectional view of an end
region of a guide cylinder remote from
the front portion of the tool of another
embodiment of a setting tool according
to the present invention.
DESCRIPTION OF A SPECIFIC EMBODIMENTS
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A setting tool according to the present invention,
which is shown in Fig. 1, is driven with high-pressure
gases, e.g., with an explosive powder charge. The setting
tool includes a housing 1 and a handle 2, which is formed as
one piece with the housing 1. A cartridge channel 4 for
receiving a strip-shaped cartridge clip with a plurality of
cartridges, not shown, extends through the handle 2. An
actuation trigger 3 is provided in the transitional region
between the housing 1 and the handle 2. The trigger 3
serves for actuating a firing mechanism not shown. A Guide
cylinder 5 and a stem 61 of a drive piston 6 project beyond
the end, in a setting direction, region of the housing 1.
The guide cylinder 5, which is shown in detail in
Figs. 2, 3 and 4, is displaceable, in a direction opposite
to the setting direction, against a biasing force of a
spring, not shown, when the setting tool is pressed against
a constructional component, likewise not shown. At its end,
opposite to the setting direction, the guide cylinder 5 has
a cartridge chamber 64 in which a cartridge, not shown, is
received.
The axially displaceable drive piston 6 is located
in the inner chamber of the guide cylinder 5. The drive
piston 6 is formed of the stem 61 and a head 62 adjoining
the stem 61. The head 62 extends radially beyond the stem
61. The cross-sectional surface of the head 62 corresponds
substantially to the inner diameter of the guide cylinder 5.
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The stem 61 has a substantially constant diameter. A stop
surface 63, which face in the setting direction, is provided
in the transition region between the stem 61 and the head
62. The inner chamber of the guide cylinder 5 has bottom
51 likewise facing in the setting direction. A channel,
which is connected with the cartridge chamber 64, opens into
the bottom 51. A discharge opening 14, which is formed in
the circumference of the guide cylinder 5, serves for
flushing the inner chamber of the guide cylinder 5.
A guide housing 7 extends parallel to the guide
cylinder 5. The guide housing 7 has a cylindrical guide
channel 71 in which a slide 73 is displaced in the setting
direction against a biasing force of a spring 8. The slide
73 has a pawl 78 pivotable about a pivot 731 against a
biasing force of a spring member 75. The pawl 78 is
provided on a side of the slide 73 adjacent to the guide
cylinder 5. A surface 782 of the pawl 78, adjacent to the
guide cylinder 5, is inclined in the setting direction. The
pawl 78 is further provided with a control profile 781
inclined in a direction opposite to the setting direction
and a stop surface 783 provided between the surface 782 and
the control profile 781.
At a side thereof remote from the guide cylinder
5, the pawl 78 has a blind bore in which at least a portion
of the spring member 75 is received. A guide member 76,
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which is formed as a bolt, projects from the pawl 78
parallel to the axis of the blind bore. The guide member 76
extend through the slide 73 and an elongated slot 74
provided in the guide housing 7. The guide member 76
prevents rotation of the slide 73 in the guide channel 71.
The guide channel 71 has, like the inner chamber
of the guide cylinder 5, a bottom 72 facing in the setting
direction and aligned with the bottom 51 of the inner
chamber of guide cylinder 5. Both the guide cylinder 5 and
the guide channel 71 are provided with elongated slots 65
and 77, respectively, extending parallel to the longitudinal
axis of the drive piston 6. A control or operating cam 13
is provided in the end region of the slot 65 opposite to the
setting direction. The operating cam 13 cooperates with the
control profile 781 of the pawl 78 in the initial position
of the slide 73.
A connection channel 10 connects the guide channel
71 with the end region of the guide cylinder 5 opposite to
the setting direction.
Fig. 5 shows a guide cylinder 105, a drive piston
106, and a guide housing 107 with a guide channel 171 in
which a slide 173 is displaced against a biasing force of a
spring not shown.
Two connection channels 110 and 150 open into the
guide channel 171 of the guide housing 107. The first
channel l10 is associated with a vent channel 160 the cross-
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section of which is varied with an adjusting member 111.
The vent channel 160 extend between the guide cylinder 105
and the atmosphere. The second channel 150 is spaced
axially, in the setting direction, from the vent channel 160
and opens into the guide cylinder 105. The two connection
channels 110 and 150 serve for directing a portion of a
high-pressure gas into the guide housing 107 where it
applies the same pressure to the slide 173 independent of
the position of the adjusting member 111 relative to the
vent channel 160 or independent of the pressure established
in the guide cylinder with the adjusting member 111. This
provides for displacement of the slide 173 in the setting
direction with a uniformly accelerated speed.
When, e.g., the entire energy of the high-pressure gas is
necessary for the displacement of the drive piston 106 in
the guide cylinder 105, the adjusting member 111 is in its
closed position, and the vent channel 160 is closed. With
the vent channel 160 being closed, the entire amount of the
high-pressure gas necessary for the acceleration of the
slide 173 is delivered into the guide housing 107 through
the connection channel 150. When a smaller pressure is
needed in the guide cylinder 105 for displacing the drive
piston 106, at least partial opening of the vent channel l60
is effected by the displacement of the adjusting member 111
in a direction opposite to the setting direction. In this
case, the high-pressure gas needed for the displacement of
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the slide 173 is delivered through the first connection
channel 110, which is connected with the vent channel 160,
and through the second connection channel 150. The inner
diameters of the channels 160, 150 and 110 and thereby the
flow velocity of the high-pressure gas in the channels 160,
150 and 110 are controlled with orifice restrictors provided
in the channels 160, l50 and 1l0.
Now, the course of a setting process with a
setting tool according to the present invention will be
described with reference to the setting tool shown in Figs.
1-4.
As discussed above, Fig. 2 shows a setting tool
with the drive piston 6 and the slide 73 in their initial
positions. The control profile 781 of the pawl 78
cooperates with the operating cam 13. The pawl 78 does not
project into the axial projection of the drive piston 6.
Shortly after the ignition of a cartridge, first
the drive piston 6 is accelerated and shortly thereafter the
slide 73 is accelerated. This position of the drive piston
6 and the slide 73 is shown in Fig. 3. The control profile
781 of the pawl 78 separates from the operating cam 13, and
the spring member 75, which is provided between the pawl 78
and the slide 73, pivots the pawl 78 into the axial
projection of the drive piston 6.
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Because the drive piston 6 has a greater
acceleration than the slide 73, the slide 73 reaches its end
position at the earliest after the drive piston 6 already
reached the end, in the setting direction, region of the
guide cylinder 5 or has rebound from the fastening element
and has been accelerated toward its initial position by the
stored residual power. In the end, in the setting
direction, position, the slide 73 rebounds from a damping
member 9.
Fig. 4 shows the drive piston 6 in an intermediate
position when the drive piston 6 is being displaced back to
its initial position. In this intermediate position, the
pawl 78 projects into the axial projection of the drive
piston 6. In order to prevent clinging of the drive piston
6 to the pawl 78, the pawl 78 has, as it has already been
described above, an inclined, in the setting direction,
surface 782 which insures pivoting of the pawl 78 out of the
axial projection of the drive piston 6 until the drive
piston 6 passes past the pawl 78.
The spring 8, which was compressed upon the
displacement of the slide 73 in the setting direction,
pushes the slide 73 to its initial position. The drive
piston 6, which has not yet reached its initial position,
has its stop surface 63 engaged by the pawl 78 which pushes
the drive piston 6 to its initial position. Shortly before
the slide 73 reaches its initial position, the control
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profile 781 of the paw 78 engages the operating cam 13 which
pivots the pawl 78 completely out of the axial projection of
the drive piston 6.
Though the present invention was shown and
described with references to the preferred embodiments,
various modifications thereof will be apparent to those
skilled in the art and, therefore, it is not intended that
the invention be limited to the disclosed embodiment or
details thereof, and departure can be made therefrom within
the spirit and scope of the appended claims.
